Magnesium

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

There are conclusive but not suffcient data for the classification of substance Magnesium with regard to mutagenicity/genetic toxicity. It is concluded that the substance Magnesium does not meet the criteria to be classified for human health hazards for Mutagenicity-Genetic Toxicity

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions (not individual results reported), acceptable, well-documented publication/study report which meets basic scientific principles.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

GLP compliance:

not specified

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase (TK) +/- -3.7.2 heterozygote of L5178 mouse lymphoma cells

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

All cells were thawed from frozen stock and maintained in Fischer's medium for leukemic cells of mice containing 10% heat-inactivated horse serum, Pluronic F68, sodium pyruvate, penicillin G, and streptomycin sulfate.
Background spontaneous TK -/- mutant frequencies were reduced weekly by 24-h treatment of the cells with medium containing thymidine, hypoxanthene, methotrexate, and glycine.

Additional strain / cell type characteristics:

other: TK +/-

Metabolic activation:

with and without

Metabolic activation system:

S9

Test concentrations with justification for top dose:

36,000 - 32,000 - 30,000 - 28,000 - 26,000 - 24,000 - 22,000 µg/ml.

Vehicle / solvent:

Sterile glass distilled water.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

Migrated to IUCLID6: with and without S9 metabolic activation. EMS was purchased from Eastman Chemicals (Eastman Kodak, Rochester, N.Y.)

Details on test system and experimental conditions:

The test system was based on the procedure described by Clive et al. (1975, 1979) with modifications to the cloning procedure.
MgCl2 were diluted in sterile glass-distilled water, and 0.1 ml of dilution was added to a 10-ml suspension containing 6 X 10E6 cells from a culture recently cleansed of TK-/- cells. When testing with activation, the 10-ml suspension included 4 ml of an appropriate dilution of S9 with cofactor mix. Cultures containing either MgCl2, positive or solvent controls were incubated for 4 h at 37°C.
After exposure, the cells were washed twice, fresh medium was added, and the cultures were carried through a 2-day expression period. The cultures were counted after day 1 and readjusted to 3 X 10E5 cells per milliliter if necessary.

On day 2 a modified cloning procedure was followed. A sample from each culture was centrifuged and the cells resuspended at 500,000 viable cells per milliliter in Fischer's medium. The concentrated cells were serially diluted and appropriate dilutions plated in triplicate in cloning medium with and without trifluorothymidine (TFT). Approximately 500,000 viable cells (as determined by exclusion of trypan blue) were plated on each of three selective medium plates containing 2 Mg/ml TFT (Sigma), and 100 cells were cloned on each of three nonselective plates for each test and control tube. Cell inocula were added directly into 100-mm tissue culture plates, followed by the addition of about 30 ml cloning medium. The plates were swirled gently to ensure even dispersal of the inocula, allowed to gel, and then incubated at 37°C for approximately 12 d before they were counted. A New Brunswick Scientific automatic colony counter was used to determine the number of colonies per plate.

Evaluation criteria:

Total survival was determined by the method of Clive and Spector (1975) which combines growth in suspension culture and soft cloning efficiency data.
The mutation frequency (MF) was calculated as the number of mutants per 105 colony-forming cells.

Statistics:

no data

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

Cytotoxicity observed at concentration of 28 mg/mL and above due to changes in osmotic pressure. See table in "any other information"

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Remarks on result:

other: strain/cell type: Thymidine kinase +/-

Remarks:

Migrated from field 'Test system'.

Mutagenic responses of Mouse lymphoma L5178Y Cells following exposure to MgCl2

Chemical	Dose (µg/ml)	Percent total survival	Mutation frequency	Increase over solvant
Solvent	0	100	17.9	-
EMS	620	20	136.3	7.6
MgCl2	36,000	1	19.0	-
	32,000	15	13.3	-
	30,000	15	16.2	-
	28,000	46	15.6	-
	26,000	75	11.6	-
	24,000	101	13.1	-
	22,000	94	14.6	-

 

Conclusions:

Interpretation of results (migrated information):
negative

The in vitro gene mutation test in mouse lymphoma cells (thymidine kinase locus in L5178Y) on the test substance shown no treatment related increase in mutation frequency.

Executive summary:

MgCl2 was examined for its potential to induce forward mutations at the thymidine kinase locus in L5178Y mouse lymphoma cells. Test doses of MgCI2 evoked little or no enhancement of mutation compared to the solvent control. Only at 36,000 µg/ml was the response to mutation frequency greater than the solvant control, and this was at 1% total survival. These results were not altered by metabolic activation of the test system. While toxicity from exposure to MgCl2 might be related only to abnormal osmotic conditions, these results suggest that low survival levels (

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

In a reliable study (Oberly, T.J. et al.1982 ), the in vitro gene mutation test in mouse lymphoma cells (thymidine kinase locus in L5178Y) on the test substance show no increase in mutation frequency.

In a reliable study (Oguma Yet al.1998) magnesium sulfate induced no increase in the number of colonies with reverse mutation in any of the strains irrespective of the absence or presence of metabolic activation in the main study. Thus, it is concluded that magnesium sulfate does not have mutagenic potential under the presence experimental conditions.

The treatment of magnesium sulfate did not induce increases in the proportion of cells with structural and numerical aberrations both in the absence and the presence of metabolic activation system. It was concluded that magnesium sulfate did not exhibited clastogenic activity in cultured Chinese Hamster Lung cells when tested under the conditions employed for this test.

Justification for classification or non-classification

Based on the hazard assessment of Magnesium in section 2.1 and 2.2. in IUCLID 5.4., available data for the substance and following the “Guidance on Information Requirement and Chemical Safety Assessment R.8. Characterisation of dose [concentration]- response for human health” andaccording to the criteria described in Directive 67/548 and in the CLP Regulation:

 

Directive 67/548	Mutagenicity-Genetic Toxicity Muta. Cat. 1; R46 May cause heritable genetic damage. Muta. Cat. 2; R46 May cause heritable genetic damage. Muta. Cat. 3; R68 Possible risk of irreversible effects.
CLP	Germ cell mutagenicity Muta. 1A Muta. 1B Muta. 2 H340: May cause genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. H341: Suspected of causing genetic defects <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.

 

 

It is concluded that the substance Magnesium does not meet the criteria to be classified for human health hazards for Mutagenicity-Genetic Toxicity